The audible effect of multiple voices sounding the same note is well known. The multiple strings of an orchestra, the multiple voices of the chorus or choir, the multiple pipes of an organ, although they may be sounding the same note, produce a different audible effect than solo voices. This effect is the result of one or more characteristics of each voice discernible by the ear. For example, the multiple voices may not be exactly in tune, that is, they may be slightly different in pitch, resulting in an audible beat frequency. They may be frequency modulated (vibrato) differently. Even if two or more voices are identical in pitch they may sound as multiple voices because the harmonic content of the respective voices may be changing differently while the voices are being sounded. Also, the amplitude envelope of the several voices may be changing differently, that is, the attack/decay characteristic of the individual voices may be different.
While multiple voices can now be created independently in known electronic musical instruments, this has been accomplished by providing a multiplicity of tone generating channels for each note. A separate channel must be employed if any of the above characteristics are to be controlled independently.